// FileSystemScanner.cs
//
// Copyright 2005 John Reilly
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.


using System;
using System.IO;

namespace ICSharpCode.SharpZipLib.Core
{
    #region EventArgs
    /// <summary>
    /// Event arguments for scanning.
    /// </summary>
    public class ScanEventArgs : EventArgs
    {
        #region Constructors
        /// <summary>
        /// Initialise a new instance of <see cref="ScanEventArgs"/>
        /// </summary>
        /// <param name="name">The file or directory name.</param>
        public ScanEventArgs(string name)
        {
            name_ = name;
        }
        #endregion
        
        /// <summary>
        /// The file or directory name for this event.
        /// </summary>
        public string Name => name_;

        /// <summary>
        /// Get set a value indicating if scanning should continue or not.
        /// </summary>
        public bool ContinueRunning
        {
            get => continueRunning_;
            set => continueRunning_ = value;
        }
        
        #region Instance Fields

        readonly string name_;
        bool continueRunning_ = true;
        #endregion
    }

    /// <summary>
    /// Event arguments during processing of a single file or directory.
    /// </summary>
    public class ProgressEventArgs : EventArgs
    {
        #region Constructors
        /// <summary>
        /// Initialise a new instance of <see cref="ScanEventArgs"/>
        /// </summary>
        /// <param name="name">The file or directory name if known.</param>
        /// <param name="processed">The number of bytes processed so far</param>
        /// <param name="target">The total number of bytes to process, 0 if not known</param>
        public ProgressEventArgs(string name, long processed, long target)
        {
            name_ = name;
            processed_ = processed;
            target_ = target;
        }
        #endregion
        
        /// <summary>
        /// The name for this event if known.
        /// </summary>
        public string Name => name_;

        /// <summary>
        /// Get set a value indicating wether scanning should continue or not.
        /// </summary>
        public bool ContinueRunning
        {
            get => continueRunning_;
            set => continueRunning_ = value;
        }

        /// <summary>
        /// Get a percentage representing how much of the <see cref="Target"></see> has been processed
        /// </summary>
        /// <value>0.0 to 100.0 percent; 0 if target is not known.</value>
        public float PercentComplete
        {
            get
            {
                float result;
                if (target_ <= 0)
                {
                    result = 0;
                }
                else
                {
                    result = (processed_ / (float)target_) * 100.0f;
                }
                return result;
            }
        }
        
        /// <summary>
        /// The number of bytes processed so far
        /// </summary>
        public long Processed => processed_;

        /// <summary>
        /// The number of bytes to process.
        /// </summary>
        /// <remarks>Target may be 0 or negative if the value isnt known.</remarks>
        public long Target => target_;

        #region Instance Fields

        readonly string name_;
        readonly long processed_;
        readonly long target_;
        bool continueRunning_ = true;
        #endregion
    }

    /// <summary>
    /// Event arguments for directories.
    /// </summary>
    public class DirectoryEventArgs : ScanEventArgs
    {
        #region Constructors
        /// <summary>
        /// Initialize an instance of <see cref="DirectoryEventArgs"></see>.
        /// </summary>
        /// <param name="name">The name for this directory.</param>
        /// <param name="hasMatchingFiles">Flag value indicating if any matching files are contained in this directory.</param>
        public DirectoryEventArgs(string name, bool hasMatchingFiles)
            : base (name)
        {
            hasMatchingFiles_ = hasMatchingFiles;
        }
        #endregion
        
        /// <summary>
        /// Get a value indicating if the directory contains any matching files or not.
        /// </summary>
        public bool HasMatchingFiles => hasMatchingFiles_;

        #region Instance Fields

        readonly bool hasMatchingFiles_;
        #endregion
    }
    
    /// <summary>
    /// Arguments passed when scan failures are detected.
    /// </summary>
    public class ScanFailureEventArgs : EventArgs
    {
        #region Constructors
        /// <summary>
        /// Initialise a new instance of <see cref="ScanFailureEventArgs"></see>
        /// </summary>
        /// <param name="name">The name to apply.</param>
        /// <param name="e">The exception to use.</param>
        public ScanFailureEventArgs(string name, Exception e)
        {
            name_ = name;
            exception_ = e;
            continueRunning_ = true;
        }
        #endregion
        
        /// <summary>
        /// The applicable name.
        /// </summary>
        public string Name => name_;

        /// <summary>
        /// The applicable exception.
        /// </summary>
        public Exception Exception => exception_;

        /// <summary>
        /// Get / set a value indicating wether scanning should continue.
        /// </summary>
        public bool ContinueRunning
        {
            get => continueRunning_;
            set => continueRunning_ = value;
        }
        
        #region Instance Fields

        readonly string name_;
        readonly Exception exception_;
        bool continueRunning_;
        #endregion
    }
    
    #endregion
    
    #region Delegates
    /// <summary>
    /// Delegate invoked before starting to process a directory.
    /// </summary>
    public delegate void ProcessDirectoryHandler(object sender, DirectoryEventArgs e);
    
    /// <summary>
    /// Delegate invoked before starting to process a file.
    /// </summary>
    /// <param name="sender">The source of the event</param>
    /// <param name="e">The event arguments.</param>
    public delegate void ProcessFileHandler(object sender, ScanEventArgs e);

    /// <summary>
    /// Delegate invoked during processing of a file or directory
    /// </summary>
    /// <param name="sender">The source of the event</param>
    /// <param name="e">The event arguments.</param>
    public delegate void ProgressHandler(object sender, ProgressEventArgs e);

    /// <summary>
    /// Delegate invoked when a file has been completely processed.
    /// </summary>
    /// <param name="sender">The source of the event</param>
    /// <param name="e">The event arguments.</param>
    public delegate void CompletedFileHandler(object sender, ScanEventArgs e);
    
    /// <summary>
    /// Delegate invoked when a directory failure is detected.
    /// </summary>
    /// <param name="sender">The source of the event</param>
    /// <param name="e">The event arguments.</param>
    public delegate void DirectoryFailureHandler(object sender, ScanFailureEventArgs e);
    
    /// <summary>
    /// Delegate invoked when a file failure is detected.
    /// </summary>
    /// <param name="sender">The source of the event</param>
    /// <param name="e">The event arguments.</param>
    public delegate void FileFailureHandler(object sender, ScanFailureEventArgs e);
    #endregion

    /// <summary>
    /// FileSystemScanner provides facilities scanning of files and directories.
    /// </summary>
    public class FileSystemScanner
    {
        #region Constructors
        /// <summary>
        /// Initialise a new instance of <see cref="FileSystemScanner"></see>
        /// </summary>
        /// <param name="filter">The <see cref="PathFilter">file filter</see> to apply when scanning.</param>
        public FileSystemScanner(string filter)
        {
            fileFilter_ = new PathFilter(filter);
        }
        
        /// <summary>
        /// Initialise a new instance of <see cref="FileSystemScanner"></see>
        /// </summary>
        /// <param name="fileFilter">The <see cref="PathFilter">file filter</see> to apply.</param>
        /// <param name="directoryFilter">The <see cref="PathFilter"> directory filter</see> to apply.</param>
        public FileSystemScanner(string fileFilter, string directoryFilter)
        {
            fileFilter_ = new PathFilter(fileFilter);
            directoryFilter_ = new PathFilter(directoryFilter);
        }
        
        /// <summary>
        /// Initialise a new instance of <see cref="FileSystemScanner"></see>
        /// </summary>
        /// <param name="fileFilter">The file <see cref="IScanFilter">filter</see> to apply.</param>
        public FileSystemScanner(IScanFilter fileFilter)
        {
            fileFilter_ = fileFilter;
        }
        
        /// <summary>
        /// Initialise a new instance of <see cref="FileSystemScanner"></see>
        /// </summary>
        /// <param name="fileFilter">The file <see cref="IScanFilter">filter</see>  to apply.</param>
        /// <param name="directoryFilter">The directory <see cref="IScanFilter">filter</see>  to apply.</param>
        public FileSystemScanner(IScanFilter fileFilter, IScanFilter directoryFilter)
        {
            fileFilter_ = fileFilter;
            directoryFilter_ = directoryFilter;
        }
        #endregion

        #region Delegates
        /// <summary>
        /// Delegate to invoke when a directory is processed.
        /// </summary>
        public ProcessDirectoryHandler ProcessDirectory;
        
        /// <summary>
        /// Delegate to invoke when a file is processed.
        /// </summary>
        public ProcessFileHandler ProcessFile;

        /// <summary>
        /// Delegate to invoke when processing for a file has finished.
        /// </summary>
        public CompletedFileHandler CompletedFile;

        /// <summary>
        /// Delegate to invoke when a directory failure is detected.
        /// </summary>
        public DirectoryFailureHandler DirectoryFailure;
        
        /// <summary>
        /// Delegate to invoke when a file failure is detected.
        /// </summary>
        public FileFailureHandler FileFailure;
        #endregion

        /// <summary>
        /// Raise the DirectoryFailure event.
        /// </summary>
        /// <param name="directory">The directory name.</param>
        /// <param name="e">The exception detected.</param>
        bool OnDirectoryFailure(string directory, Exception e)
        {
            DirectoryFailureHandler handler = DirectoryFailure;
            bool result = (handler != null);
            if ( result ) {
                ScanFailureEventArgs args = new ScanFailureEventArgs(directory, e);
                handler(this, args);
                alive_ = args.ContinueRunning;
            }
            return result;
        }
        
        /// <summary>
        /// Raise the FileFailure event.
        /// </summary>
        /// <param name="file">The file name.</param>
        /// <param name="e">The exception detected.</param>
        bool OnFileFailure(string file, Exception e)
        {
            FileFailureHandler handler = FileFailure;

            bool result = (handler != null);

            if ( result ){
                ScanFailureEventArgs args = new ScanFailureEventArgs(file, e);
                FileFailure(this, args);
                alive_ = args.ContinueRunning;
            }
            return result;
        }

        /// <summary>
        /// Raise the ProcessFile event.
        /// </summary>
        /// <param name="file">The file name.</param>
        void OnProcessFile(string file)
        {
            ProcessFileHandler handler = ProcessFile;

            if ( handler!= null ) {
                ScanEventArgs args = new ScanEventArgs(file);
                handler(this, args);
                alive_ = args.ContinueRunning;
            }
        }

        /// <summary>
        /// Raise the complete file event
        /// </summary>
        /// <param name="file">The file name</param>
        void OnCompleteFile(string file)
        {
            CompletedFileHandler handler = CompletedFile;

            if (handler != null)
            {
                ScanEventArgs args = new ScanEventArgs(file);
                handler(this, args);
                alive_ = args.ContinueRunning;
            }
        }

        /// <summary>
        /// Raise the ProcessDirectory event.
        /// </summary>
        /// <param name="directory">The directory name.</param>
        /// <param name="hasMatchingFiles">Flag indicating if the directory has matching files.</param>
        void OnProcessDirectory(string directory, bool hasMatchingFiles)
        {
            ProcessDirectoryHandler handler = ProcessDirectory;

            if ( handler != null ) {
                DirectoryEventArgs args = new DirectoryEventArgs(directory, hasMatchingFiles);
                handler(this, args);
                alive_ = args.ContinueRunning;
            }
        }

        /// <summary>
        /// Scan a directory.
        /// </summary>
        /// <param name="directory">The base directory to scan.</param>
        /// <param name="recurse">True to recurse subdirectories, false to scan a single directory.</param>
        public void Scan(string directory, bool recurse)
        {
            alive_ = true;
            ScanDir(directory, recurse);
        }
        
        void ScanDir(string directory, bool recurse)
        {

            try {
                string[] names = Directory.GetFiles(directory);
                bool hasMatch = false;
                for (int fileIndex = 0; fileIndex < names.Length; ++fileIndex) {
                    if ( !fileFilter_.IsMatch(names[fileIndex]) ) {
                        names[fileIndex] = null;
                    } else {
                        hasMatch = true;
                    }
                }
                
                OnProcessDirectory(directory, hasMatch);
                
                if ( alive_ && hasMatch ) {
                    foreach (string fileName in names) {
                        try {
                            if ( fileName != null ) {
                                OnProcessFile(fileName);
                                if ( !alive_ ) {
                                    break;
                                }
                            }
                        }
                        catch (Exception e) {
                            if (!OnFileFailure(fileName, e)) {
                                throw;
                            }
                        }
                    }
                }
            }
            catch (Exception e) {
                if (!OnDirectoryFailure(directory, e)) {
                    throw;
                }
            }

            if ( alive_ && recurse ) {
                try {
                    string[] names = Directory.GetDirectories(directory);
                    foreach (string fulldir in names) {
                        if ((directoryFilter_ is null) || (directoryFilter_.IsMatch(fulldir))) {
                            ScanDir(fulldir, true);
                            if ( !alive_ ) {
                                break;
                            }
                        }
                    }
                }
                catch (Exception e) {
                    if (!OnDirectoryFailure(directory, e)) {
                        throw;
                    }
                }
            }
        }
        
        #region Instance Fields
        /// <summary>
        /// The file filter currently in use.
        /// </summary>
        readonly IScanFilter fileFilter_;
        /// <summary>
        /// The directory filter currently in use.
        /// </summary>
        readonly IScanFilter directoryFilter_;
        /// <summary>
        /// Flag indicating if scanning should continue running.
        /// </summary>
        bool alive_;
        #endregion
    }
}
